In a standard glass-plate or ceramic cooking unit the cooking pots and pans are set down directly on locations on a ceramic panel under which are respective gas burners. Each of these burners is associated with a respective igniter typically constituted as a resistive wire that is heated by passing an electric current through it and that is positioned in the path of the gas issuing from the respective burner so that such gas is ignited by it. The amount of gas fed to each burner is controlled by a respective valve having an indicator and also usually associated with a temperature-responsive controller to maintain a desired temperature in the respective burner.
Normally the igniter is energized only when the respective burner is turned on to ignite it. In order to ensure that the flame is properly lit, since failure to ignite would not be as readily noticed as on an open-flame system, it is standard to place in parallel to the on/off switching contacts for each burner a switching circuit or the like that itself is closed when the respective burner is turned on but that remains closed until a temperature sensor associated with the respective burner location on the ceramic panel determines that the respective location has reached the desired temperature. Such a supplementary igniter-control system is fairly expensive and constitutes another heat-exposed element that can fail and require servicing.